This application is submitted to permit the purchase of a sensitive amino acid analyzer system that will make it possible to determine amino acid compositions of acid hydrolysates of very small amounts of peptides. The sensitivity of this instrument is about two orders of magnitude better than that of the existing instrument. Several recent examples are shown to illustrate the present difficulty of having access to peptide microsequencing at the 200 pmol level but being unable to confirm sequences by amino acid analysis because of the relatively low sensitivity of the present amino acid analyzer. The new system will be especially important for analysis of brain and gut hormones and neuropeptides purified from limited human tissue sources. It also will be applied to analysis of membrane proteins, hormone precursors, and enzyme fragments and active site peptides. In many cases, amino acid analysis combined with amino terminal analysis and HPLC maps of proteolytic peptide fragments will obviate the need for multiple amino acid sequence determinations.